Nxp B.v.

Koninklijke Philips Corporation N.v.

Koninklijke Phillips Electronics N.v.

Adam Brown

Godefridus A M Hurkx

Wiebe B De Boer

Eddie Huang

Hendrik G A Huizing

Keith Heppenstall

Adrian Koh

Ian Kennedy

A transistor () has a FET () and a temperature sensing diode () integrated within it. Gate drive circuit () is arranged to switch off FET () and in this case biasing circuit () drives a constant current through the diode (). The voltage across the diode () is measured by voltage sensor () which provides a measure of the temperature of the FET.

MOSFET with temperature sense facility

The invention relates to FETs with stripe cells (). Some of the cells have alternating low and high threshold regions () along their length. In a linear operations regime, the low threshold regions conduct preferentially and increase the current density, thereby reducing the risk of thermal runaway. By distributing the low threshold regions () along the length of the cells (), the risk of current crowding is reduced.

Insulated gate field effect transistors

A trench-gate MOSFET or ACCUFET has its gate ( ) in a first trench ( ) that extends through a channel-accommodating body region ( ) to a drain region ( ). Within the transistor cells, a second trench ( ) comprising deposited highly-doped semiconductor material ( ) extends to the drain region ( ). This highly-doped material ( ) is of opposite conductivity type to the drain region ( ) and, together with a possible out-diffusion profile ( ), forms a localized region ( ) that is separated from the first trench ( ) by the body region A source electrode ( ) contacts the source region ( ) and the whole top area of the localized region ( ). In a MOSFET, the localized region ( ) provides protection against turning on of the cell's parasitic bipolar transistor. In an ACCUFET (FIG. ), the localized region ( ) depletes the channel-accommodating body region ( A). In both devices the localized region ( ) is well-defined and can be narrow to enable a small transistor cell size. Furthermore, before filling the second trench ( ) with its semiconductor material ( ), the drain region ( ) can be readily provided with an avalanche-breakdown region ( ) at the bottom of the second trench ( ), for example by implanting dopant ions ( ) of the same conductivity type as the drain region ( ). This avalanche-breakdown region ( ) improves the ruggedness of the device. It can also aid current spreading ( ) in the drain region ( ) in the conductive state of the transistor.

Trench-gate semiconductor devices

The invention relates to a so-called punch-through diode with a mesa ( ) comprising, in succession, a first ( ), a second ( ) and a third ( ) semiconductor region ( ) of, respectively, a first, a second and the first conductivity type, which punch-through diode is provided with two connection conductors ( ). During operation of said diode, a voltage is applied such that the second semiconductor region ( ) is fully depleted. A drawback of the known punch-through diode resides in that the current flow is too large at lower voltages. In a punch-through diode according to the invention, a part ( A, B) of the second semiconductor region ( ), which, viewed in projection, borders on the edge of the mesa ( ), is provided with a larger flux of doping atoms of the second conductivity type than the remainder ( A) of the second semiconductor region ( ). It has been found that the high current at a low voltage of the known diode is caused by the fact that the second semiconductor region ( ) at the edge of the mesa ( ) is depleted before the remainder of the second semiconductor region ( ). By locally increasing the flux of doping atoms, the depletion at the edge is delayed as compared to the remainder of the second semiconductor region. Preferably, this result is obtained by locally increasing the thickness of the second semiconductor region ( ). In this manner, a substantial current reduction at lower voltages is obtained in the diode in accordance with the invention.

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Bramhall, United Kingdom

Adam Brown